Waitangi Stream Remediation and Erosion Protection

The Waitangi Stream is controlled by the Bay of Plenty Regional Council and is used to control levels in Lake Ōkāreka. In late 2017 flows were increased beyond the streams capacity causing major scouring of one stream section, putting houses above at risk and damaging the natural environment.

The site was accessed via a private road which was owned by a number of concerned land owners. Stakeholder management was a high priority. The stream is situated 8m below road level, with very difficult access. MAP developed a method to protect the fresh water flowing through the site while safely and efficiently constructing the project.

The stream flows were first reduced to minimum levels. A small digger was then craned into the stream where a diversion pipe was installed along the existing stream invert. A manhole at the top of the site was installed and stream flows diverted through the manhole and into the diversion pipe. This allowed flows to return to normal while works took place, while allowing for the entire site to be built in the dry, fully protecting the stream and the local environment.

A ramp was constructed with imported fill down into the work site. From here, MAP crews completed hard filling, rip rap placement, and 190 gabion baskets. Our crews worked in very tight conditions through the winter months to complete the works on time before fish spawning season. Finally landscaping works were completed.

Various stream flows were tested through the site with fantastic results, and the client and adjacent land owners were very happy with the final works.